As expressed in the title of this specification, the present invention, refers to blood pumping equipment for extracorporeal circulation, whose purpose is to substitute the pumping action of the heart of a patient when the patient is subjected to heart surgery, it likewise being useful as a support means of ventricular assistance, respiratory assistance and cerebral percussion, without ruling outs its use in dialysis.
The purpose of the invention is to integrate in a single fungible unit the elements or means that are used in pumping blood for extracorporeal circulation, permitting the replacement of this unit or assembly after each operation, with a minimum loss of time, easy assembly/disassembly and with an economic cost much lower than that implied by systems or equipment used conventionally for the same purposes, eliminating the length of tubes and the volume of blood that would be involved. Basically, the equipment comprises a reservoir receiving the patient""s venous blood; an impulsion pump of that blood; a heat exchanger for thermal conditioning of the blood and an oxygenator, all complemented with corresponding valves in order to form a single assembly or unit that permits a pulsatile blood flow to be provided with adjustable flow and frequency, by the doctor himself or controlled by a signal of the patient""s electrocardiogram.
As is well known, heart surgery in extracorporeal circulation operates on a stopped heart, therefore it is necessary to temporarily substitute the functioning thereof by means of a system that externally pumps the blood, thus maintaining the blood perfusion to the brain and to the rest of the vital organs of the body.
Nowadays the main types of systems used in the pumping of blood are based on peristaltic or centrifugal pumps. Both systems provide a flow fixed by unit of time, therefore in order to increase the flow its speed must be increased, which leads to the continuous blood diverging very considerably from the natural pulsatile flow generated by the human heart.
Taking into account that the greater the disparity between the natural blood flow and the flow generated by the pumping system, the greater the physiological deterioration suffered by the patient, it is evident that it proves to be logical and desirable to achieve the greatest approximation between the extracorporeally pumped blood flow and the natural pulsatile flow.
Systems or equipment that efficiently carry out this function are unknown, irrespective of the fact that current systems are constituted by several parts that need to be coupled together before the operation, having high losses of charge, and the subsequent loss of time in the preparation, and, what is even more important, without the desired optimum results.
Besides, it must be taken into account that the equipment used is disposed of after each operation, which implies a high cost.
The equipment object of the invention, provided for the pumping of blood for extracorporeal circulation and ventricular assistance, constitutes a unit or assembly integrated with an operating principle that permits the programming of pumping flows and frequency in an independent manner, with the particularity that the impulsion pump may be controlled by a computer (according to the doctor""s orders or as of a measured physiological parameter), which permits the obtainment of flow and pressure waves with characteristics close to those existing in normal physiological operation.
Therefore, it may be said that the equipment of the invention implies a structurally simple solution with absolute functional reliability, for the purpose for which it has been developed, maintaining its fungible characteristics.
In this sense, the equipment in question is constituted as of a pump with a bellows-type piston, which comprises a chamber in which the piston itself is arranged, piston integral to a through shaft, in a sealed manner, through a cover that closes the bottom base of the chamber, whose shaft is operated by means of a servomotor related to a suitable mechanism that transforms the angular alternate movement at the outlet of the servomotor into linear alternate movement that is applied to the shaft of the piston, so that the piston is displaced alternately in an axial manner in the inside of the chamber, in order to achieve in one direction of displacement the input of the patient""s venous blood to the chamber, and to produce in the other direction of displacement the impulsion of the blood to the outside from said chamber for the oxygenation thereof.
In relation to the cited chamber established in the impulsion pump, the same is communicated on the one hand with a reservoir or tank to which the patient""s venous blood accedes, reservoir that is placed above the chamber and integral to the body thereof. In the inside of the chamber, specifically in the area of passage or communication thereof with the reservoir, there is a float sealing valve, which due to its low density with regard to that of the blood is pushed by the blood towards the closing position, when the blood contained in the chamber is impelled by the piston (by means of expansion of the bellows) towards the outlet nozzle, while when the piston is displaced in the opposite direction (the bellows contracts), increasing the capacity of the chamber, the valve is separated from the passage of communication with the reservoir, opening said passage and permitting the access of the venous blood from the cited reservoir to the chamber itself.
Therefore, the chamber from which the pumping of the blood takes place is variable in amplitude, which permits the variation of the flow maintaining the frequency and vice versa, therefore said two parameters may be controlled independently in order to adapt them to the patient""s or doctor""s needs.
The body of the cited chamber is assembled, with ease of becoming independent, on a base with suitable displacement means, such as wheels, that allow easy transfer of the equipment from one place to another; locking and securing means of said assembly having been provided for between said two parts, with the particularity that the bottom one constituting the cited base carries the mechanism that transform the rotating movement of the servomotor into alternate linear movement on the shaft of the piston, the servomotor also being assembled on said base.
On the other hand, a ball-check valve that closes the passage by gravity has been provided for on the duct corresponding to the outlet nozzle of the chamber in which the impulsion pump is established, in such a way that the opening is carried out only when the blood is impelled from the pump. After said ball-check valve a heat exchanging device is inserted, as a thermal conditioning means of the blood and, connected to the latter, a oxygenating device, from which the oxygenated blood comes out through a nozzle, returning to the patient. Said thermal conditioning and oxygenating devices are integral to the block formed by the reservoir and body of the pump, in such a way that said components or elements, including the valves, form a fungible assembly or unit, easily assembled/disassembled with regard to the base.
The cited integration gives rise to a single fungible unit or assembly, and entails the elimination of the operative phases in order to carry out the coupling of all of the independent elements, intercommunicating them with tubes, which implies a saving of material, installation and final disassembly time, to which it is necessary to add the saving of volume of blood existing in the circuit outside of the patient, a fact which is of the utmost importance, aside from eliminating with this part of the effect of hemolysis that the cited tubes produce.
The incorporation of a programmable automaton or computerized console, that governs the servomotor in order to control the movement of the bellows-type piston and consequently the flow and frequency of the pump, is also characteristic of the invention, the programming being carried out by means of a PC on the market, that makes the calculations and establishes the communication with the automaton that controls the servomotor, there also being a screen for direct control of said automaton, it being possible to achieve that the performance of the equipment is similar to that of human physiological behavior, with some pressure and flow curve diagrams similar to those of the behavior of the blood system, evidencing the similarity achieved in the parameters achieved with elasticity in frequency, volume, pressure and curve form.
The fact that the equipment may be provided with an autonomous operation system should be pointed out, by means of an electric feed battery, that permits the patient to be transported while some organ of his is being assisted by the proposed equipment, it also being provided for that the computerized console and the equipment itself are connected to each other by means of a cable with an indefinite length, permitting the equipment to be located next to the patient or next to the surgeon, the console being able to be separated in a second plane.
Finally, the possibility of providing the equipment with means to adjust its operation tempo should be cited, means alternate to the console, for the purpose of permitting the use thereof without conventional electric feed.